I would argue it's the proper tools for the job, and in a real fight the F-35 has its place but I doubt would take on every role. The F-35 was designed as a day 1 strike fighter, to go in to areas where the enemy capabilities are at full strength and 4th gen aircraft survivability would be very low. Once the threat level is lower then the cheaper and more numerous 4th gen F-16s, F/A-18s, A-10s can go in to clean up. First choice for air superiority would be the F-22. That's what it was built to do and pretty much all their pilots train to do. As the threat level lowers then F-15s would pick up the slack. Depending on the theatre, there would also be Rafales, Typhoons and maybe even Gripens in the mix. All very capable modern aircraft.
I think there is a lot of evidence to show that although the aircraft you're flying can give you an advantage, it's the pilot at the controls (and their training) that makes the difference. WWII I firmly believe it was Allied doctrine to pull experienced aces off the front lines and make them instructors that made the biggest difference. Instead of using that one ace to try to rack up as many kills as they can until they have a bad day, then that experience is gone forever, send him home to make 100 more just like him. Allied aircraft were not overwhelmingly superior to Axis aircraft by the end of the war, we see it in the MA all the time where an expertly flown K4 or Dora can mop the floor with anything the Allies have.
Even more modern examples, 4th gen aircraft have scored kills on F-22s and F35s during training. I've even heard of T-38s getting kills on F-22s on the odd day where the T-38 pilot is on top of their game and nothing's going right for the F-22 pilot. This is pure speculation (really most of this post is) but I would think in major ops like Red Flag where the world is watching, the powers that be are going to stack the deck to make sure bluefor looks as good as possible.
That's not knocking the F-35. I think it does what it was designed to do very well and has a lot of things going for it that helps the pilot do their thing and get home safe. But IMO it was hampered by the requirement that 3 very different aircraft must fit in the same airframe. Some sacrifices were made in performance and capabilities that could have been avoided if 3 separate aircraft had been developed.
Anyway that's my very non-expert opinion
